In article , Lobster
writes

unfortunately the (LV) plug which
connects to the monitor is slightly but crucially differently sized to the
original, so it won't fit - both are standard-looking concentric plugs (ie
this sort of thing: http://tinyurl.com/mx35688) but the central pin is
evidently larger on the monitor than it was on my netbook (though the
external diameter looks the same). What are the specs for these things -
how do I work out what plug I need to buy?

It's a 3.5mm jack plug, but they come with internal diameters of 2.1 and
2.5mm. Your 'new' PSU has the 2.1mm 'ole and you're trying to get it
into a socket with the 2.5mm pin.

Cut the cable off the dead PSU and splice it onto the working one. Use
heatshrink sleeving to make a neat joint.

And DOUBLE CHECK you have the polarity right if you don't want to let
the magic smoke out.

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